In general, a storage region is duplicated in different storage devices so that data is managed for the purpose of preventing the data from being lost when one of the storage devices fails or for another purpose.
In recent years, the capacity of a memory device that is included in a storage device has increased. With the increase in the capacity, a time period for copying data has increased. Thus, a rotational rate of a disk of the memory device has increased.
However, due to the increase in the rotational rate of the disk of the memory device, it may be difficult to synchronize the timing of a data copy operation in the storage device, and, as a result, the number of failures to copy data may increase. When a failure to copy data occurs in the storage device, the storage device re-performs an operation of acquiring, from the memory device, the data that has not been successfully copied. When the storage device performs this operation, a time (seek time) for causing a reading device (head) included in the memory device to move above a disk occurs. Thus, there is a problem that a time period that is necessary to copy data increases.